Bipolar membrane

Abstract

A bipolar membrane which exhibits a low water dissociation voltage for an extended period of time under a high current density condition, and a high current efficiency, without developing blister. The bipolar membrane comprises a cation-exchange membrane and an anion-exchange membrane which are joined together, wherein ion-exchange resin particles having ions exchanged with ions of a metal of an atomic number 20 to 90, such as titanium, zirconium, tin, iron, ruthenium or palladium, or with complex ions of said metal are existing on the junction interface between the cation-exchange membrane and the anion-exchange membrane.

What is claimed is:  
     
       1. A bipolar membrane comprising a cation-exchange membrane and an anion-exchange membrane which are joined together, wherein ion-exchange resin particles having ions of a metal of an atomic number 20 to 90 or having complex ions of said metal are existing on the junction interface between the cation-exchange membrane and the anion-exchange membrane. 
     
     
       2. A bipolar membrane according to  claim 1 , wherein the metal of an atomic number 20 to 90 is a metal of the Group IV or of the Group VIII of periodic table. 
     
     
       3. A bipolar membrane according to  claim 2 , wherein the metal of the Group IV or of the Group VIII of periodic table is at least one metal selected from the group consisting of iron, titanium, tin, zirconium, nickel, palladium and ruthenium. 
     
     
       4. A bipolar membrane according to  claim 1 , wherein the ion-exchange resin particles having ions of a metal of an atomic number 20 to 90 or having complex ions of said metal, are the ion-exchange resin particles having ions being exchanged with ions of the metal of an atomic number 20 to 90 or with complex ions of said metal. 
     
     
       5. A bipolar membrane according to  claim 1 , wherein the ion-exchange resin particles are forming a layer on the junction interface between the cation-exchange membrane and the anion-exchange membrane. 
     
     
       6. A bipolar membrane according to  claim 5 , wherein the layer of the ion-exchange resin particles has an average thickness of from 0.02 to 100 μm. 
     
     
       7. A bipolar membrane according to  claim 5 , wherein a ratio of the area of the layer of the ion-exchange resin particles and the area of the whole junction surface is from 1 to 99% as a ratio of the area projected onto a plane in parallel with the surface of the membrane. 
     
     
       8. A bipolar membrane according to  claim 1 , wherein the ion-exchange resin particles are the ones having ions exchanged with the ions of a metal of an atomic number 20 to 90 or with complex ions of said metal over a range of 0.1 to 100% of the whole ion exchange capacity. 
     
     
       9. A bipolar membrane comprising a cation-exchange membrane and an anion-exchange membrane which are joined together, wherein ion-exchange groups having ions of a metal of an atomic number 20 to 90 or having complex ions of said metal are existing on at least one surface facing the junction interface of the cation-exchange membrane and the anion-exchange membrane, and ion-exchange resin particles having ions of a metal of an atomic number 20 to 90 or having complex ions of said metal are existing on the junction interface between the cation-exchange membrane and the anion-exchange membrane. 
     
     
       10. A bipolar membrane according to  claim 9 , wherein the metal of an atomic number 20 to 90 is a metal of the Group IV or of the Group VIII of periodic table. 
     
     
       11. A bipolar membrane according to  claim 10 , wherein the metal of the Group IV or of the Group VIII of periodic table is at least one metal selected from the group consisting of iron, titanium, tin, zirconium, nickel, palladium and ruthenium. 
     
     
       12. A bipolar membrane according to  claim 9 , wherein the ion-exchange resin particles are the ones having ions exchanged with the ions of a metal of an atomic number 20 to 90 or with complex ions of said metal over a range of 0.1 to 100% of the whole ion exchange capacity. 
     
     
       13. A bipolar membrane according to  claim 9 , wherein the cation-exchange membrane and/or the anion-exchange membrane are the ones having ions exchanged with the ions of a metal of an atomic number 20 to 90 or with complex ions of said metal over a range of 0.001 to 100% of the whole ion exchange capacity.